#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <string.h>
int main()
{
	char arr[1024] = { 0 };
	while (scanf("%s", arr) != EOF)
	{
		int len = strlen(arr);
		for (int i = 0; i < len - 1; i++) 
		{
			for (int j = 0; j < len - 1 - i; j++)
			{
				if (arr[j] > arr[j + 1])
				{
					char ch = arr[j];
					arr[j] = arr[j + 1];
					arr[j + 1] = ch;
				}
			}
		}
		printf("%s\n", arr);
	}
	return 0;
}